Open Sourcing a Vertical Market Application?

BigCanOfTuna asks: "The company I work for is considering the possibility of turning over one of thier enterprise applications to the open source community. They are doing this for a number of reasons including raising thier profile in the OS community, developing relationships with other Energy companies that would be willing to hire us as consultants, and of course just for good will (if there is such a thing in business!). Since the application is very specific to a vertical market, can one expect to see the same results that other open source projects see? Are there any other successful OS projects out there that are geared to a specific niche?"